This application claims the benefit of priority based on German Application No. 19912256.3, filed on Mar. 18, 1999, which is incorporated by reference herein in its entirety
The invention relates to a method of manufacturing an electronic apparatus and to an electronic apparatus with a plastic housing, especially an electronic control apparatus for automotive technology.
Electronic apparatuses or control apparatuses which have a plastic housing are usually manufactured by injection molding. In the case of injection molding at least two housing parts are produced. A circuit board is next placed and fastened in at least one of the housing parts. The housing parts are then assembled and bonded together. Therefore, in manufacturing the apparatus, a plurality of operations must be performed.
In the periodical xe2x80x9cKunststoffe,xe2x80x9d published by Carl Hanser Verlag, Munich, Vol. 80 (1990), no. 12, pp 1333-1345 and Vol. 81 (1991), no. 1, pp 27-35, there is disclosed the production of plastic hollow goods by blow molding. An advantage of blow molding is that hollow goods can be manufactured in a single piece, which avoids problems with sealing. Also, such a single piece has great stability and rigidity. Although tools for blow molding are relatively economical, it is difficult to manufacture hollow goods of more complicated geometry (e.g., undercutting) by blow molding.
German Patent No. 44 20 879 A1 discloses s a conventional method of manufacturing hollow bodies with an internal supporting frame. A housing enveloping the supporting frame is made by blow molding methods. After the housing is filled it has to be closed-up with a floor and a cover.
German Patent No. 41 20 670 A1 discloses a conventional method for manufacturing a three-dimensional circuit substrate by blow molding.
German Patent No. 197 07 437 A1 discloses a conventional method for the manufacture of a multi-part housing by draw molding two pieces of film, whereby two housing shells are formed, Which are then cemented or welded together.
It is an aim of the present invention to create a method for manufacturing an electronic apparatus and an electronic apparatus with a plastic housing, which permit an especially simple and economical manufacture.
According to the invention, the fixing and mounting of the circuit board is integrated into the process for manufacturing the plastic housing, so that the separate insertion of the circuit board into the housing is eliminated.
A circuit board can be provided with a one-piece housing in the form of a hollow body. The populated circuit board is surrounded during the extrusion process with a tube of plastic that is viscous when heated. In this process the circuit board is embedded into the material of the plastic housing at least partially at its edges.
The method and the electronic apparatus are suitable for control apparatus and sensors, especially in automotive engineering. For example, in connection with air bag controllers and air bag sensors, it is especially advantageous that the housing can be formed by blow molding such that the housing is in contact in the area of a mounting point both with the bottom and with the upper side of the circuit board. The result is an optimal transfer of impulses from the vehicle""s body to an acceleration sensor arranged in the apparatus.
The present invention is achieved by providing a method of manufacturing an electronic apparatus. The method comprises providing an electronic circuit board; and blow molding a one-piece plastic housing around the electronic circuit board such that the electronic circuit board is secured by the plastic housing.
The present invention is also achieved by providing a method for transferring impulses from a vehicle body to an electronic sensor. The method comprises mounting the electronic sensor on an electronic circuit board; blow molding a one-piece plastic housing around the electronic circuit board and the sensor such that the electronic circuit board is secured to the plastic housing; and fixing the one-piece plastic housing to the vehicle body.
The present invention is further achieved by providing an electronic apparatus. The electronic apparatus comprises a one-piece plastic housing made by blow molding; an electronic circuit board secured in-situ during blow molding the plastic housing; and at-least one location wherein the plastic housing contiguously sandwiches the electronic circuit board.